Salts of antimony (V) esters as flame retardants

ABSTRACT

Water soluble salts of antimony (V) glycol esters are useful flame retardants for such materials as textiles or polymeric resins. These flame retardants are applied together with a source of organic halogen. A typical such salt is tri(ethylenedioxy)hydrogen antimony (V), sodium salt.

United States Patent Knowles 1 Oct. 7, 1975 I l SALTS ()F ANTIMONY (V)ESTERS AS FLAME RETARDANTS [56] References Cited {75] Inventor: RichardNorris Knowles, Hockessin, OTHER PUBLICATIONS Mann, The HeterocyclicDerivatives of Phosphorus [731 Assignee: E. I. Du Pont de Nemours andArsenic, Antimony and Bismuth, 2nd Edit, Wiley-Int Company, Wilmington,Del. erscience. N.Y., pp. 611, 612, 620, 621, (1970).

[22] Filed: Jan. 22 1974 Primary ExummerHelen M. S Sneed [21] Appl. No.1435,493

Related US. Application Data [57] ABSTRACT [62] Division Of 8C1, N0.2(l4,7U4 Dec. 3 l97l, Pat. NO. water sglukfle alts of antimony gIy Iesters are 3336557- useful flame retardants for such materials astextiles 0r polymeric resins. These flame retardants are applied I52] CL2601,4299; 7/136; 252/81; together with a source of organic halogen. Atypical 252/8-6; 260/2 EP? 260/25 A]? 260/285 such salt istri(ethylenedioxy)hydrogen antimony (V),

260/429 R; 260/446 Sodium Sam [51] Int. Cl. C07F 3/06 58 Field of Search260/4299 l m N0 Drawings SALTS ()F ANTIMONY (V) ESTERS AS FLANIE'RETARDANTS This is a division of application Ser. No. 204.704. filedDec. 3. 1971 now U.S. Pat. No. 3.836.557.

BACKGROUND OF THE INVENTION This invention relates to novel.water-soluble. stable salts of antimony (V) glycol esters. useful asflame retardantsv Various antimony compounds have been used heretoforeas flame retardants. The most commonly used compound is antimonytrioxide. When used as a flame retardant for farbics. antimony trioxidehas the drawback of being insoluble in water or other common solvents.and it thus cannot be introduced within the fiber. Antimony trioxidcapplied to the outside of the fiber is subjected to mechanical wear andabrasion and is readily lost from the surface, unless special bindersare used. These binders. such as ethylenevinyl acetate copolymer. makethe fabric stiff and they are suitable only for use in tents.tarpaulins, etc.

Antimony (V) salts. such as antimony pentachloride. are decomposed bywater with the liberation of the corresponding acid. such ashydrochloric acid. They are,

therefore. unsuitable for use as flame retardants in many situations.Various antimonatcs. such as sodium antimonate or potassium antimonate,also are known; however. their low solubility in water limits their use.Antimony (V) esters also are known. Some of the esters are highlysensitive to moisture. decomposing readily in moist air. Several estersof antimony (III) and antimony (V) are disclosed in US. Patv No.3.()3l,425 to be useful flame retardants. While conventional antimony(V) esters are soluble in organic solvents and can be incorporated intoorganic polymers, they are less suitable for use in hydrophilic fibersor fabrics, such as cotton. which always contain water within thefibers.

There is a need. therefore, for water-stable. flame retardant antimonycompositions which can be introduced into hydrophilic materials and canbe insolubilized therein.

SUMMARY OF THE INVENTION According to this invention. there are providednovel salts of antimony (V) glycol esters. which have the followingFormula l J:

wherein each of R. and R independently is hydrogen or methyl; M is thecation of lithium. sodium. potassium. magnesium. calcium. strontium.barium. zinc. cadmium. guanidinium. ethylencdiammonium. or ammoniumhaving the following formula (2):

oil

wherein each of R R and R independently is hydrogen. methyl. ethyl. orZ-hydroxyethyl; and .t' is the va lence of the cation and has the valueof l or 2.

The novel salts of antimony (V) esters of the present invention areuseful flame retardants for textile materials or polymeric resins towhich they are applied, providing a source of organic halogen also ispresent.

DETAILED DESCRIPTION OF THE INVENTION The novel compounds of thisinvention are reasonably stable in water at room temperature above a pHof about 2.5. Below a pH of about 2.5, rapid hydrolysis of the estersoccurs and antimony oxides precipitate. The preferred pH range, withinwhich the novel compounds are most stable. is about 6-9. The stabilityin water of these compounds varies with the cation, the salts ofunivalent cations being more stable than the salts of divalent cations.

Representative salts of antimony (V) esters of the present inventioninclude those listed below in Table I. They are named salts oftri(alkylenedioxy)hydrogen antimony (V), ie the compound which would beobtained by substituting H from M in Formula l above.

TABLE I Tri(ethylenedioxy)hydrogen antimony (V). sodium saltTri(ethylenedioxy)hydrogen antimony (V). lithium saltTri(ethylenedioxy)hydrogen antimony (V). potassium saltTri(ethylenedioxy )hydrogen Tri( ethylenedioxy )hydrogen antimony (V).zinc salt antimony (V). barium salt Tri(ethylenedioxy)hydrogen antimony(V). strontium salt Tri(ethylenedioxy)hydrogen antimony (V), calciumsalt Tri(ethylenedioxy)hydrogen antimony (V), cadmium saltTri(ethylenedioxy)hydrogen antimony (V). magnesium saltTri(ethylcncdioxy)hydrogen antimony (V), ammonium salt Tri(ethylenedioxy )hydrogen ylammonium salt antimony (V).trimethethylenediammonium salt tri(dimethylethylcnedioxy)hydrogenantimony (V),

sodium salt These salts can be characterized by their elementalcomposition and their nuclear magnetic resonance spectra. as shown inExamples 25. below. It is noteworthy that these salts are much morestable in water than the parent acids. which decompose extremely rapidlyin water. A typical such acid is tri(ethylenediox hydrogen antimony (V).

The stability in water of the novel salts of this invention also dependson the nature of the cation, the less amphoteric the cation the morestable being the salt. This can be shown by heating aqueous solutions ofthe salts. A comparison of the stability of several salts oftri(ethylenedioxy)hydrogen antimony (V) in distilled water is presentedin Table ll, below:

TABLE ll Cation Temperature at Which a Precipitatc is Formed Na Noprecipitate after I minute at ltKlC Mg Precipitate forms at about 90C BaPrccipitatc forms at about 75C Zn" Prccipitatc forms at about 65C Noprecipitate forms when aqueous solutions of the ammonium and guanidiumsalts are heated for l minute at 100C, indicating that the stability ofthese salts is comparable to that of the sodium salt.

The salts of these antimony (V) esters can be made by neutralization ofthe corresponding acids (hydrogen compounds) with appropriate bases,such as hydroxides or carbonates. The neutralization is carried out in asolvent that must satisfy the following two requirements:

l. the parent acid must be soluble in it, and

2. the addition of water, in amounts up to weight percent of the totalsolvent mixture, must not result in the formation of antimony oxideprecipitates. The only solvents meeting these requirements are glycolswith vicinal hydroxyl groups. In each case, the preferred solvent is theglycol used to make the ester. For example, ethylene glycol should beused for the tri(ethylenedioxy)esters and l,2-dihydroxy propane for thetri(methylethylenedioxy) esters. This is preferred to avoid undesirableester interchange.

The salts can be made in these solvents in the presence of up to about30 weight percent of water, based on the total weight of the solventmixture. When larger quantities of water are present. the base catalyzedhydrolysis of the ester interferes with the preparation of pure salts.When crystalline salts are to be isolated, it is usually preferred tokeep the water content of the medium below about I571 by weight of thetotal solvent mixture.

During the neutralization reaction, the temperature of the solutionshould be kept below that at which the salt decomposes; usually,however, a temperature below C. is preferred.

The starting acids (hydrogen compounds) are made by a reaction ofantimony trioxide with appropriate glycol having vicinal hydroxyl groupsand hydrogen peroxide to oxidize antimony to the pentavalent state. Thereaction can be carried out by adding hydrogen peroxide to either l aslurry of antimony trioxide in the glycol or (2) a solution of anantimony (Ill) ester of the glycol. The preparation oftri(ethylenedioxy)hydrogen antimony (V) is described in Example 1,below, to illustrate this process.

The salts of divalent cations, which are less soluble than those ofunivalent cations, can also be made from the latter by metathesis with asoluble salt of the divalent cation in mixtures of vicinal hydroxylglycols and water. By properly selecting the concentration andtemperature, the divalent salt will precipitate and may be recovered inreasonably pure form.

These pentavalent antimony ester salts can be used in combination withan organic halogen source to impart flame retardancy to textiles and tovarious polymeric materials. When aqueous or alcoholic solutions ofthese salts are applied to cellulose-containing materials, antimony iscarried into the fibers, where it can be insolubilized by heating or bylowering the pH to below about 2.5. The location of antimony oxides deepwithin the fiber makes them more resistant to laundering and weathering.The solid antimony oxides which precipitate are more finely divided and,hence, more efficient than commercial antimony trioxide as a flameretardant.

The preferred solvents for applying the novel antimony ester salts tocellulosic materials are water, ethylene glycol, l,2-dihydroxypropane,2,3- dihydroxybutane, and their mixtures. The source of halogen is bestincorporated into the cellulosic material after solid antimony oxideshave been precipitated.

Chlorwax 500 (a hydrocarbon containing about 60% chlorine, sold byDiamond Shamrock Corp.) and Dechlorane Plus 25 (a chlorinated organiccompound sold by Hooker Chemical Co.) are examples of halogen sourcesthat can be used with these pentavalent antimony ester salts ontextiles. The halogen will be either chlorine or bromine.

These pentavalent antimony salts can be used at levels ranging fromabout 0.5 to l0?! by weight, based on the finished article. Below 0.5%poor flame retardancy is observed, and above l07r additionalimprovements in flame retardancy are not sufficient to justify thehigher cost. The amount of the halogen is from about 5'7: to 30% basedon the weight of the finished article.

The dry pentavalent antimony ester salts can also be incorporated intovarious polymers such as halogenated polyester resins to enhance theirflame retardancy. The finely ground salt is stirred thoroughly into ahalogenated, unsaturated polyester, such as Diamond Shamrocks Dionresin. Benzoyl peroxide can then be added. and a solid polyesterpanelcan be fabricated whose flame retardancy rating in the HLT-lS test ishigher than in a panel made from the Dion resin alone. The HLT- l 5 testis described by R. E. McMahon et al., 25th Annual Technical Conference,1970, Reinforced Plastics/ Composites Division of the Society of thePlastics industry, lnc., in Section 9-C, pages l-l2.

It is not necessary to use an additional halogen source when the polymeritself already is halogenated. Other polymeric materials that can bemade flame retardant by the process of the present invention include thefollowing: halogenated polyurethanes, plasticized polyvinyl chloride,halogenated epoxy resins, and halogenated polycarbonates.

The following examples will serve to illustrate the pentavalent antimonyester salts, their method of synthesis and their use as flame retardantmaterials. ln these examples, all percentages are by weight.

EXAMPLE I This example describes the preparation of crystallinetri(ethylenedioxy)hydrogen antimony (V) from antimony trioxide, ethyleneglycol, and hydrogen peroxide. Seven hundred and ninety grams of H gradeantimony trioxide supplied by the McGean Chemical Company of Cleveland.Ohio [5.43 moles of Sb (111)] and 3750 grams of ethylene glycol wereadded to a 5 liter roundbottom flask equipped with two dropping funnels.a mechanical stirrer. vacuum distillation apparatus, and a thermometer.The pressure of the system was reduced to 216 torr., and the slurry washeated vigorously. When the temperature reached about l50C., thesolution began to boil, liberating the water formed in the reaction ofthe ethylene glycol and the antimony trioxide. After about 45 minutes,200 ml. of distillate was collected and the temperature rose to 160C. Atthis point about /3 of the Sb had reacted.

The pressure of the system was reduced to 190 torr., and the dropwiseaddition of a 30.2% solution of hydrogen peroxide was started. Fivehundred and thirty-six grams (4.75 moles H 0 of hydrogen peroxide wasadded over a 3-hour, 13 minute period. During this period the water wasremoved continuously by distillation with about four parts of ethyleneglycol per part water. This distillate contained about 100 ppm H 0Ethylene glycol was added to maintain the weight of the solution atabout 4000 grams. As the oxidation and esterification reactionsproceeded, more Sb 0 reacted and dissolved. After about 60% of theperoxide was added, the solution became clear. The temperature of thesolution remained between l45C. and [50C.

When the starting Sb 0 contained orthorhombic crystals, filtration atthis point was necessary in order to remove this insoluble material.

After this part of the addition was completed the so lution was analyzedfor Sb(lll). The method was a potentiometric titration with abromide-bromate solution of the sample dissolved in hydrochloric acid.The end point was determined by a sudden increase in the potential of aplatinum-calomel electrode system. The solution of mixed Sb(lll) andSb(V) ethylene glycol esters was found to contain 156 grams of Sb(lll)(1.27 moles). Thus, 4.16 moles of the starting Sb(lll) were converted toSb(V) by 4.75 moles of hydrogen peroxide; an 87.5% utilization ofperoxide was realized. An additional 143 grams of 30.2% hydrogenperoxide 1.27 moles) was now added in a similar manner as the firstportion. The solution was again analyzed and found to contain 70.5 gm.of Sb(lIl) (.63 mole). A 50% utilization of the peroxide was obtained inthe second addition.

To complete the reaction, the solution was cooled to l C. and 70 gramsof peroxide solution was added over a l minute period at atmosphericpressure. After 2 minutes the solution temperature was l22C. This stepconverted about 70% of the remaining Sb(lll) to Sb( V).

Then. the water and some excess ethylene glycol were removed by vacuumdistillation. The pressure was gradually reduced to 5 torr.. and thesolution temperature was about 100C. When the weight of solution wasreduced to about 3500 gm. the Sb(V) ethylene glycol ester began tocrystallize from the solution. Excess glycol was removed until thesolids content of the slurry was so high that stirring became difficult.The weight of the slurry was 2220 grams, and its temperature was thenabout 120C.

The vacuum was released and I200 ml. of tetrahydrofuran was added todilute the slurry and to facilitate its filtration. The crystals werefiltered under a blanket ofdry nitrogen. The wet crystals ere thenwashed with 2.5 liters of tctrahydrofuran and dried at room temper aturewith a stream of dry nitrogen. Fourteen hundred and sixty-nine gramsoftri(ethylenedioxy )hydrogen antimony( V) were obtained. Thecrystalline product contained 40.5% Sb( V) and 0.025% Sb(lll). The Sb(V)was determined by dissolving the crystals in hydrochloric acid, addingpotassium iodide and titrating the liberated iodine with sodiumthiosulfate solution. (Details of the analytical procedure are given inStandard Methods of Chemical Analysis published by D. Van Nostrand &Co., Inc., Princeton, N..l., pp. -76, 1939.)

The Sb(lll) was analyzed according to the procedure given earlier inthis example.

Calcd. for C,,H O Sb: C, 23.8, H, 4.3: Sb, 40.3%. Found: C, 23.9; H,4.3; Sb, 40.6%.

To complete the material balance, the mother liquor was titrated andfound to contain 23.8 grams of Sb(lIl) and 34.5 grams of Sb(V). Thus,99% of the antimony charged was accounted for and 90.0% of it wasconverted to crystalline tri(ethylenedioxy) hydrogen antimony (V).

EXAMPLE 2 The tri(ethylenedioxyJhydrogen antimony (V), sodium salt wasprepared as follows.

Tri(ethylenedioxy)hydrogen antimony (V) g; 0.497 mole) was dissolved ina solution consisting of 650 g of ethylene glycol and 80 g of distilledwater. The pH of this solution was 0.4. A 50% aqueous sodium hydroxidesolution (38.5 g; 0.480 mole) was added slowly to the stirred solutionover a 40 minute period; the temperature was kept between 29 and 35Cwith gentle cooling. At this time, the pH was 6.9. Crystals oftri(ethylenedioxy)hydrogen antimony (V), sodium salt began to separatenear the end of the sodium hydroxide addition. Approximately 40 minutesafter the end of the sodium hydroxide addition a thick slurry ofcrystals was present. The slurry was cooled to 05C. held at thattemperature for thirty minutes, and then filtered. The white,crystalline product was washed with acetone and dried under nitrogen.The yield was 79.2% of crystals melting at l28.5l30.0C.

Calcd. for C,,H NaO Sb'3 ethylene glycol: C. 28.2; H, 5.9; Na, 4.5; O,37.6; Sb, 23.8%.

Found: C, 28.1; H. 6.0; Sb, 23.8%. N.M.R. and LR. spectroscopic data forthis salt are given in Table [ll of Example 5.

When this salt was subsequently dried over phosphorus pentoxidc at 110C. and 0.2 mm of mercury, the three ethylene glycol moles ofcrystallization were removed. The resulting crystals were distinctlyhexagonal. They appeared to sinter at about 180C, but did not melt below260C.

Calcd for C,;H, NaO ,-Sb: C, 22.2; H, 3.7; Na, 7.1;0, 29.6; Sb, 37.4%.

Found. C, 21.9; H, 4.4; Sb, 37.7%.

EXAMPLE 3 To a solution of tri(ethylenedioxy)hydr0gen antimony (V),sodium salt (37.2 g; 0.104 mole) in a mixture consisting of 650 g ofethylene glycol and 80 g of water was added 14.2 g ofa 50% aqueous zincchloride solution (7.1 g active; 0.052 mole). The solution was placed ina refrigerator at about 5C for 3 days. The crystals which separated werefiltered, washed sequentially with acetone and diethyl ether, and thendried under nitrogen. The dense, white crystals (12.0 g) melted atl54l57C.

Calcd. forC,- H O Sb Zn'7H O: C. 18.3; H. 4.8; O. 38.2; Sb. 30.6; Zn,8.2%. Found: C. 18.3; H. 4.7; Sb. 29.5; Zn. 8.2%. N.M.R. and l.R.spectroscopic data for this salt are given in Table III of Example 5.

EXAMPLE 4 A solution of tri(ethylenedioxy)hydrogen antimony (V) (5.0 g;0.0166 mole) in a mixture of 23 g ofethylene glycol and 3 g of water wasprepared. Guanidine carbonate 1.50 g; 0.0083 mole) was added withstirring. When carbon dioxide evolution ceased. the solution was leftstanding at room temperature for 3 days. The line needles whichseparated were filtered and washed with ether. The melting point washigher than 260C.

Calcd for C H N O -Sb'ZH O: C, 21.1; H. 5.7; N. 10.6; Sb. 30.6%. Found:C, 21.6; H. 4.7; N, 10.6; Sb, 31 1'72.

N.M.R. and LR. spectroscopic data for this salt are given in Table 111of Example 5.

EXAMPLE 5 The N.M.R. spectra of the salts of this invention sup port theassigned structure of these salts. In Table I are spectral data for thesodium. zinc, and guanidine salts, along with the free acid forcomparison. Hexadeuterodimethyl sulfoxide was used as the solvent andtetramethylsilane (TMS) was used as the internal standard. All peakpositions are repeated as 5 from TMS.

Table IV Continued Order of Intensity (the lowest number denotes thehighest intensity) Compound Peak (Cm l 105 1075 1038 N95 877 1 108 1040X98 H77 1 108 1033 8'90 875 l 105 108K 103K 890 Sodium salt a il Zincsalt (iuanitline Salt Sodium Salt EXAMPLE 6 EXAMPLE 7 The magnesium saltof tri(ethylenedioxy)hydrogen antimony (V) can be prepared according tothe method of Example 3 by substituting magnesium chloride for the zincchloride.

TABLE III Peak Relative Compound Multiplicity Area Assignment Free Acid5.72 Singlet Acidic hydrogen 1.65 Singlet Hydrogens in ethylenedioxybridges 3.45 Singlet Hydrogens in ethylene glycol methylenes (trace ofethylene glycol present) Sodium Salt 4.50 Broad singlet l8 Ethyleneglycol of crystallization 3C H O 3 52 Singlet Hydrogens in ethylenedioxybridges (the }equal 56 addition of several drops of water moved 4.41Singlet the 450 peak under the 352 peak. and the spectrum becameidentical with that of the zinc salt shown below) Zine Salt 3.52 Singlet(broadened base) Hydrogens in ethylcncdioxy bridges with 1.42 Singlet(3.52 peak much H O of crystallization under 3.52 peak.

larger than 3.42 pcakl (iuanidine 4.61 Singlet 32 (iuanidine hydrogensand hydrated water Salt 3.66 Broad singlet 44 Hytlrogens inethylenedioxy bridges.

3.5K Singlet Ethylene 4.60 Singlet 42 Hydroxyl hydrogens Glycol 3.45Singlet Kl Methylene hydrogens Sodium Salt 3.52 Singlet Hydrogcns inethylenedioxy bridges.

The LR. spectra of the salts of this invention have EXAMPLE 8 four orfive highly characteristic bands in the 85012()0 5 5 cm region; the dataare summarized in Table IV. The most notable spectral change is theshift of 1088 cm ethylene glycol peak to the 1105-1108 cm region; thispeak also becomes much weaker.

The ammonium salt of tri(ethylenedioxy)hydrogen antimony (V) can beprepared according to the method of Example 4 by substituting ammoniumearbonate for the guanidine carbonate.

EXAMPLE 9 The tri(methylethylenedioxy)hydrogen antimony (V). sodium saltcan be prepared according to the method of Example 2 by substitutingtri(methylethylenedioxy)hydrogen antimony (V) for the triethylenedioxyhydrogen antimony (V). and ll-dihydroxypropane for the ethylene glycol.

EXAMPLE a) The trilethylenedioxy)hydrogen antimony (V). I50 g; 0.497mole) can be dissolved in a mixture consisting of 650 g of ethyleneglycol and 80 g of distilled water. This solution can be further dilutedwith I30 g of distilled water. This solution can then be treated with38.5 g of a 50% aqueous sodium hydroxide solution according to Example2; the triethylenedioxy hydrogen antimony (V), sodium salt is formed.

EXAMPLE 1 l The barium salt of tri(ethylencdioxy)hydrogen antimony (V)can be prepared according to the method of Example 3 by substitutingbarium chloride for the zinc chloride.

EXAMPLE l2 A l g sample of tri(ethylenedioxy)hydrogen antimony (V),sodium salt (0.031 mole) was dissolved in l7 ml of distilled water atroom temperature; this was a 37% by weight solution. This solution wasstirred while 4.2 g of a 50% aqueous zinc chloride (().0l mole) solutionwas added dropwise over a period of several minutes. A white precipitatebegan to form shortly after the first few drops of the zinc chloridesolution had been added. The slurry was stirred for ten minutes. andthen it was filtered. The solids were washed sequentially with l0 ml ofwater and 50 ml of acetone. The dry crystals had the same melting pointand spectra as the salt prepared in Example 3.

EXAMPLE 13 A 7.0 X 25.4 cm sample of 80 X 80 cotton print cloth waspadded to a 100')? add-on with a 16% solution of(tricthylenedioxy)hydrogen antimony (V). zinc salt in ethylene glycol.The fabric was dried in a forced draft textile curing oven at 149C(300F) for 2 minutes. The fabric was then placed in an atmosphere ofsteam for ten minutes. The fabric was then dried at 79C 175F) for lminute and allowed to equilibrate with the atmosphere. The fabric had a[61% pick-up of the antimony salt. The fabric was then washed for 5minutes in cold water, dried and weighed again after equilibration. Thefabric still contained l2.371 of the antimony compound. The fabric waswhite after this test.

In a similar experiment. a sample of 80 X 80 cotton cloth was padded toa 100% add-on with a l6% slurry of antimony trioxide. The fabric wasdried for 2 minutes at 149C (300F). The fabric was allowed toequilibrate with the atmosphere; the add-on was l [5%. The fabric wasthen washed in cold water for 5 minutes, dried and weighed again afterequilibration. The fabric contained 2.8% antimony compound. The fabricwas white after this test.

These two tests show that the antimony oxides deposited within the fiberby the tri(ethylenedioxy)hydrogen antimony (V). zinc salt treatment aremore difficult to remove than the antimony trioxide deposited on thesurface of the fibers.

EXAMPLE l4 Suitable flame retarded fabric can be prepared by treatingfabric first with tri(ethylenedioxy)hydrogen antimony (V). zinc saltaccording to Example l3. The fabric can then be coated with an emulsionconsisting of 7r Chlor 500 (a liquid, chlorinated hydrocarbon) and 25%Elvax (an ethylene-vinylacetate copolymer). The application rate of thisemulsion is adjusted to give an add-on of approximately 20%. This fabricwill then pass the American Association of Textile Chemists andColorists vertical flame test 34-]969.

EXAMPLE l5 In another flame retardant applicationtri(ethylenedioxy)hydrogen antimony (V). zinc salt was ground to pass a60 mesh screen. This powder l .5 g) was then stirred thoroughly into 50g of Dion FR6399 (a brominated. unsaturated polyester resin formulationsold by Diamond Shamrock Co. This combination was stirred for 20 minutesat 3540C. Then 0.5 g of benzoyl peroxide was added, and the mixture wasstirred at 42C for 20 minutes. This mixture was then poured into a mold,and pressed at 29.000 psi on the 2.56 in. diameter (6.50 cm) pistonaccording to the following heating schedule:

Time Temperature l5 minutes (19C I75F) 20 minutes l07(' (225F) 20minutes I35C (275F) gen antimony (V).

1. THE DIVALENT ZINC SALT OF TRI(ETHYLENEDIOXY)HYDROGEN ANTRIMONY (V)